Method for polymerization of fluorine-containing haloolefins

ABSTRACT

A method for polymerization of fluorine-containing haloolefins which comprises subjecting one or more kinds of polymerizable fluorine-containing haloolefins to suspension polymerization in an aqueous medium in the presence of di(perchlorofluoroacyl) peroxide of the formula: WHEREIN N IS AN INTEGER OF 1 TO 10. Compared with known organic peroxides, the polymerization initiator of the present invention is advantageous in affording polymers of high molecular weight in excellent yields.

United States Patent Kometani et al.

[ 51 June 20, 1972 METHOD FOR POLYMERIZATION OF FLUORINE-CONTAINING HALOOLEFINS Yutaka Kometani, Nishinomiya;

Masayoshi Tatemoto; Masanori Nakamura, both of Osaka-fu, all of Japan Daikin Kogyo Co., Ltd., Osaka-shi, Osakafu. Japan Filed: April 21, 1970 Appl. No.: 30,572

Inventors:

Assignee:

Foreign Application Priority Data April 21, 1969 Japan ..44/31128 US. Cl. ..260/87.5 A, 260/87.7

Int. Cl. .i C08f1/60, C08f ill 1, C08f 3/20 Field of Search ..260/87.5, 92.1

References Cited UNITED STATES PATENTS 1/1955 Young et al. ..260/92.8

PERCENT TRANSMISSION Dittman et al 260/875 Dittman et al. ..260/92.l

Primary Examiner-Joseph L. Schofer Assistant E.\'aminer.lohn A. Donahue, J r. AnorneyCraig, Antonelli, Stewart & Hill [57] ABSTRACT A method for polymerization of fluorine-containing haloolefins which comprises subjecting one or more kinds of polymerizable fluorine-containing haloolefins to suspension polymerization in an aqueous medium in the presence of di(perchlorofluoroacyl) peroxide of the formula:

0 0 .2 cm: w: some i gc-o-o ic m0 F10 i-cnncl wherein n is an integer of l to 10. Compared with known organic peroxides, the polymerization initiator of the present invention is advantageous in affording polymers of high molecular weight in excellent yields.

6 Claims, 3 Drawing Figures WAVE I000 NUMBER (cm") PATENTEDJuTT20 I972 FIOI FIG. 2

SPECIFIC MELT VISCOSITY (POISE) 20 I I I I I I I WAVE 4000 5500 5000 2500 2000 I900 I800 I700 600 NUMBER I00 (cm') 20 T WAVE 4000 3500 3000 2500 2000 I900 I800 I700 I600 2 3 4 5 TIME OF HEAT TREATMENT (HOURS) METHOD FOR POLYMERIZATION OF FLUORINE- CONTAINING HALOOLEFINS The present invention relates to a method for polymerization of fluorine-containing haloolefms. More particularly, it relates to a method for suspension polymerization of fluorinecontaining haloolefins in the presence of polymerization initiators.

For suspension polymerization of haloolefins, there have been known two types of polymerization initiators, i.e. inorganic polymerization initiators and organic polymerization initiators. Compared with inorganic polymerization initiators such as potassium persulfate, organic polymerization initiators such as organic peroxides are known to give generally polymers of better thermal stability. When, however, organic peroxides free of fluorine are used for polymerization of fluorine-containing haloolefins, a non-fluorinated radical is introduced as the terminal group so that the thermal stability of the produced polymers is made insufficient and unsatisfactory. Moreover, in many cases, such organic peroxides produce polymers only in low yields or require high temperatures and pressures. As the fluorine-containing organic peroxide useful as a polymerization initiator, there is known di(perfluoroacyl) peroxide of'the formula:

wherein B is hydrogen or fluorine and m is an integer of 2 to 24 for polymerization of ethylenically unsaturated monomers in the absence of water [U.S. Pat. No. 2,559,630]. But, the initiator is hydrolyzed in the presence of water so that the initiation efficiency is extremely lowered and the conversion of the monomers into the polymers is much decreased.

As the results of the study seeking the polymerization initiators suitable for suspension polymerization of fluorine-containing haloolefins in an aqueous medium, it .has been found that di( perchlorofluoroacyl) peroxide of the formula:

wherein n is as defined above is quite excellent for such use. The presence of a relatively small amount of the polymeriza: tion initiator [l] in the reaction system for polymerization of fluorine-containing haloolefins produces the polymers of high molecular weight in excellent yields. Further, the initiation efficiency is so good that the polymers of desired average molecular weight are obtainable by appropriate selection of the concentration of the polymerization initiator, the temperature for polymerization and the time of polymerization. The present invention is based on the above finding.

In accordance with the present invention, there is provided method for polymerization of fluorine-containing haloolefins which comprises subjecting one or more kinds of polymerizable fluorine-containing haloolefins to suspension polymerization in an aqueous medium in the presence of the polymerization initiator [l].

The polymerization initiator [I] may be producedjfor instance, from a low polymer of chlorotrifluoroethylene according to the following scheme [U.S. Pat. No. 2,559,630]:

Examples of the polymerization initiator [I] are as follows:

Of these, the ones wherein n is an integer of l to 3 are preferred. The polymerization initiator [I] wherein n is more than 4 is isolatedwith much difficulty from the reaction mixture and relatively small in solubility into various solvents but is comparatively resistant to hydrolysis.

As the fluorine-containing haloolefins, there may be exemplified tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, chlorotrifluoroethylene, vinyliden e fluoride, vinyl fluoride, etc. The fluorine-containing haloolefins may be subjected to polymerization of this invention alone or in combination with one or more other polymerizable monomers such as vinyl monomers, acrylic monomers and styrol monomers The operation for polymerization may be per se conventional.

Practical and presently-preferred embodiments of the present invention are illustratively shown in the following examples wherein parts and percent are by weight.

EXAMPLE 1 M In an autoclave equipped with a stirrer, 150 parts of deoxygenated water are charged. After replacing the air by chlorotrifluoroethylene, parts of chlorotrifluoroethylene are admitted thereto under pressure. A calculated amount of the polymerization initiator of the formula: (RfCO) 0 in 20 to 50 percent trichlorotrifluoroethane solution is added to the autoclave. Then, polymerization is carried out.

The conditions for polymerization, the yield and flow value of the obtained polymer and the initiation efficiency are shown in Table l. The flow value, which denotes an empirical index indicating the relative molecular weight of the polymer, is determined by the Koka flow tester (manufactured by Shimadzu Seisakusho Co., Ltd.) using a die of 1 mm in nozzle diameter and 1 mm in nozzle length and 2 g of the polymer at 230 C. under 100 kg load [of T. Arai: A Guide To The Testing Of Rhedogical Properties With Koka Flow Tester" published by Maruzen Co., Ltd. on Feb. 25, 1958 Hitherto, it is known that the polymerization of chlorotrifluoroethylene at a relatively high temperature affords the polymer of low molecular weight. Therefore, it is essential to effect the polymerization at a low temperature for production of the polymer of high molecular weight. in the suspension polymerization in an aqueous medium, however, the temperature around 5 C. is the lower limit which can be adopted. The decomposition rate of fluorinated diacyl peroxide in the presence of water is considerably large even around 5 C. and so high above 20 C. that the period of half decay is shorter than 16 hours (cf. Table 3 as hereinafter shown). When the time of polymerization is long, the concentration of TABLE 1 Polymerization conditions Amount oi initiator Reac- Conver- Flow (mol Temtion sion on value Monomer pereent/ perature time monomer (10 ml./ Initiation Number Initiator, Ri (parts) monomer) 0.) (hours) (percent) see.) efficiency 1 01(C2F3CD2CF2 100 0.019 61 01(C2F3CD2CF2 100 0.045 5 65 CI(C2F3C1)2CF2 100 0.045 63 Cl(C2F C1)2CF2 100 0.020 63 CI(C2F3CI)2CF2 100 0.020 19 Cl(C2F Cl)CFz 100 0.024 7.5 48 Cl(CzF3Cl)CF2 100 0.024 25 18 H(C2F4) 100 0. 058 5 48 H(CzF4) 100 0. 058 35 48 H(C2F4)2 100 0. 121 5 48 H(C2F4)z 100 0. 121 15 48 H(C2F4)2 100 0. 121 35 48 H(C2F4)s 100 0.027 5 48 CF3(C2F4) 100 0.027 5 48 15 CF3(C2F 100 0.027 35 48 NOTE.NOS. 1 to 7 are embodiments of the invention and Nos. 8 to 15 are controls.

the polymerization initiator in the reaction system is markedly changed. From Table 1 as hereinabove shown, it can be seen that di(perfluoroaceyl) peroxide and di( -hydroperfluoroacyl) peroxide are low in the initiation efficiency, while culated according to the following equation:

wherein A and A are respectively the absorbances at 980 cm and 2350 cm in the infrared absorption spectrum meadi(perchlorofluoroacyl) peroxide is highin the initiation effi- 25 surq n h film ofabout 2 mils of thickness. and Produces the l y ofhigh molecular ght. The specific melt viscosity indicates the apparent melt viscosity measured at 380 C. under a shearing stress of 0.457 EXAMPLE 2 .kg/cm That is, this value is determined using the Koka flow In the same manner as in Example 1, various fluorine-con- .tester in the following manner: the P y is Charged in a cylinder of 9.5 mm in inner diameter, retained at 380 C. for 5 minutes and pushed out through an orifice of 2.1 mm in inner polymerization initiator, i.e. diisopropyl peroxydicarbonate. ,d mq aqq 8 m lqngth gpgicr a pi t load 95 $5; F The results are shown inlable 2. rate of pushing out (g/minute) is divided by 53,150 to give the h ze qteprepyl ne 99mm?) qfthse y e sc i 31 3?;

taining haloolefins are subjected to polymerization using di(trichlorooctafluorohexanoyl) peroxide and a known TABLE 2 a Polymerization conditions Amount of Ininitiator Reactrinsie (mol Tempertion vis- Num- Monomer percent] atnre time Yield eosity Solvent" in measurement ber Monomer Initiator (parts) monomer) C.) (hlS.) (percent) ([q]) of intrinsic viscosity 16 Diisopropyl peroxydiear- 0.3 20 24 2. 5 100 ml. dimethylacet- Vinylidene bonate. aml e 1g. 17 fluoride. Di(triehlorooctafiuorohex- 60 0.35 20 35 92 10. 4 100ml. dimethylanoyl) peroxide. acetamide/l g.

18 Vinylidene Diisopropyl peroxydi- 43-7 0.15 20 5 63 2.1 100 ml. dimethylfluoride: carbonate. aeetamide/l g. 20 tetrafiuoro- Di(trieh1orooctafluoro- 43-7 0. 15 20 5 9. 9 ml. dimethylethylene. hexanoyl) peroxide. acetamide/l g.

20 Diisolprop l peroxydi- 60 0.085 35 6 58 2. 8 100 mtl. dirie/l'ihyl- 02.1 0X18 e. 368 am} 0 g. 21 Vinyl flmnde Di(triehlorooctafiuoro- 50 0.35 20 6 a7 5.5 100m1.dimethy1- hexanoybperoxide. acetamide/l g.

22 Chlorotrifluoro- Diisopropyl peroxydicar- 42-8 0.2 40 18 54 1. 8 100 m1. cyclohexanonell ethylene: bonate. g. 23 vinyl Di(trichlorooctafiuoro- 42-8 0. 2 20 18 78 6. 7 100 ml. cyclohexanone/l hexanoyl) peroxide. g.

chloride.

EXAMPLE 3 afluoropropylene content, 13.2 percent. Specific melt viscosi- Iz-i. 13. 92959:

g EXAMPLE 4 In an autoclave equipped with a stirrer, 1,500 parts of deionized and deoxygenated water and 1.5 parts of NaHCO are charged. After replacing the air by nitrogen gas and then evacuating,,600 parts of hexafluoropropylene and 50 parts of tetrafluoroethylene are admitted thereto under pressure while maintaining the temperature at 25 C.- Stirring is then started, and 2.5 parts of a 0.82 g/ml solution of di( 1,2,4-trichloroperfluorohexanoyl) peroxide in trichlorotrifluoroethane are 4 added thereto. Polymerization starts at once whereby the 70 depression of pressure occurs. In order to maintain the pressure of the reaction system at about 10 kglcm tetrafluoroethylene is occasionally supplemented. The polyerization is carried out for 3.5 hours, and the monomer is removed. The produced polymer in powder is washed with 75 water and dried at 70 C. for 48 hours. Yield, parts. Hexln the same manner as in Example 3 but using 1.0 part of a 0.82 g/ml solution of di( l,2,4-trichloroperfluorohexanoyl) iperoxide in trichlorotrifluoroethane, the polymerization is carried out for 4.5 hours to obtain parts of the polymer. il-lexafluoropropylene content, 10.0 percent. Specific melt viscosity, 1.97 X 10 poise.

REFERENCE EXAMPLE In an autoclave equipped with a stirrer, 1,500 parts of deionized and deoxygenated water are charged, and the air is .'replaced by hexafluoropropylene. After admitting 300 parts of tetrafluoroethylene thereto under pressure, the temperature is raised up to 95 C. A solution of 0.15 part of ammonium persulfate in 20 parts of water is added, and stirring is carried out for 15 minutes. To the autoclave, 80 parts of tetrafluoroethylene are admitted, and a 5 percent aqueous solution of ammonium persulfate is continously introduced at a rate of 1.1 parts per minute. The polymerization starts at once and is effected for 80 hours, during which tetrafluoroethylene containing 8 percent of hexafluoropropylene is occasionally introduced to prevent the depression of pressure. Then, the monomer is released. The

um peroxide in an aqueous solution of sodium chloride at a temperature below C. A percent solution of the thus prepared acyl peroxide in trichlorotrifluoroethane is subjected to measurement of the decomposition rate and the activationenergy at 5 and 23 C. The parameters after addition of a nearly equal amount of water to the amount of trichlorotrifluoroethane are also measured. The results are shown in Table 3.

TABLE 3 Decomposition rate constant: Kd (minr Activation energy 5 C. 23 C. (KcaL/mol) 'Irlchloro- Trichloro- Trichloro- 'Ir chlorotrifluoro- Trichlorotriiiuoro- Trichlorotrifluorotnfiuoroethane plus trifiuoroethane plus trifluoroethane plus Number Initiator, Rf ethane water ethane water ethane water 24 Cl(CFzCFCDCF: 0.0070 0. 0054 0.30 0. 29 34 19 25 CKCFQCFCDQCFZ 0. 0077 0.0077 1.36 1.38 29 29 26.. H(C2F4)2 0. 0086 0. 044 0.15 0. 23 26 H(C2FI)3 0. 0079 0.031 0.15 0.20 27 17 23 CF3(C:F4) 0. 0042 0. 043 0.10 0.14 29 8-10 Measured at 35 C.

Nora-Nos. 24 and are embodiments oi the invention and Nos. tojsare controls.

resultant white aqueous suspension is admixed with 800 parts of acetone and stirred vigorously. The separated polymer is collected by filtration, washed with water and dried to give 420 parts of white, powdery polymer. Hexafluoropropylene content, 13.3 percent. Specific melt viscosity, 4.9 X 10 poise.

The infrared absorption spectra of the tetrafluoroethylene :he luoroprolyene copolymers obtained in Example 3 and Refernoe Example are respectively shown in FIGS. 1 and 2 of the accompanying drawings, from which it is seen that the latter copolymer has the absorptions at 3,560, 3,080, 1,815 and 1,780 cm" for the terminal carboxyl group, whereas the former copolymer has no such absorption.

When the said copolymers are burnt at 360 C. in nitrogen stream, the copolymer of Reference Example is colored blackish brown, while that of Example 3 is not colored at all.

When the said copolymers are burnt at 340 C. in an air bath, the changes of the melt viscosities are as showrrin FIG. 3 of the accompanying drawings, from which it is seen that the melt viscoty of the copolymer of Reference Example is mar kedly raised (Curve A) while that of the copolymer of Examwhereinnisanintegerofl to 10. r

2. The method according to claim 1, wherein the polymerizable fluorine-containing haloolefin is chlorou-ifluoroethylene.

3. The method according to claim 1, wherein the polymerizable fluorine-containing haloolefin is vinylidene fluoride.

4. The method according to claim 1, wherein the polymerizable fluorine-containing haloolefins are pie 3 (Curve B) shows almost no change. Thus, the latter is ex: tetrafluorocthylene and hexafluoropropylene.

tremely stable.

An acyl peroxide of the formula: (RtCO),0 is prepared by reacting an acid chloride with a slightly excess amount of sodi- 5. The method according to claim 1, wherein n is l. 6. The method according to claim I, wherein n is 2. 

2. The method according to claim 1, wherein the polymerizable fluorine-containing haloolefin is chlorotrifluoroethylene.
 3. The method according to claim 1, wherein the polymerizable fluorine-containing haloolefin is vinylidene fluoride.
 4. The method according to claim 1, wherein the polymerizable fluorine-containing haloolefins are tetrafluoroethylene and hexafluoropropylene.
 5. The method according to claim 1, wherein n is
 1. 6. The method according to claim 1, wherein n is
 2. 